A front fork for suspending a front wheel of a saddle-ridden vehicle is, for example, known. Further, some of dampers built in front forks can adjust a damping force.
JP2008-14431A discloses a damper main body including a cylinder which is connected to an outer tube, a piston which is slidably inserted into the cylinder to partition the interior of the cylinder into a compression side chamber and an extension side chamber, and a piston rod which is inserted into the cylinder and one end of which is connected to the inner tube slidably inserted into the outer tube and the other end of which is connected to the piston.
This damper main body includes a passage for allowing communication between the compression side chamber and the extension side chamber of the damper main body, a check valve provided at an intermediate position of the passage for permitting only a flow from the compression side chamber toward the extension side chamber or conversely permitting only a flow from the extension side chamber toward the compression side chamber, a needle valve provided at an intermediate position of the passage, and a stepping motor fixed to the other end of the piston rod for driving the needle valve.
This front fork exerts a damping force by giving resistance to the flow of hydraulic oil by a piston valve provided in the piston at the time of extension and exerts a damping force by giving resistance to the flow of hydraulic oil exiting from the cylinder to a reservoir by a base valve provided at an end part of the cylinder at the time of contraction. Further, by driving the needle valve to adjust flow passage resistance at the needle valve, the damping force generated by the front fork can be changed.